| 摘要 |
PURPOSE:To produce a fan with a consistent quality and to improve an entire heating efficiency, by constituting a hot air circulation type oven such that a circulation fan to be fitted to a heating chamber wall has its blade formed by bending the recessed part of metallic plate substantially to a right-angle. CONSTITUTION:In manufacturing a hot air circultion fan 8, slit recesses are defined over a metallic disc which is then bent along a recessed periphery substantially to a right-angle for thereby forming a blade 8a. By so arranging, the blade 8a can be formed to have a precisely uniform height and a balanced configuration even if a plate material of different thickness is used, and thereby reducing the parts number and the weight. As a result, the fan can increase its r.p.m. and consequently an air velocity and an air volume. Furthermore, by limiting the diameter of punch hole defined in the rear wall of heating chamber, opened areas of blow-out and suction ports can be made as small as possible, and thereby allowing an ample air velocity as necessary for cooking operation. This arrangement can ensure the manufacture of stable quality fan, which leads to the improvement in heat efficiency. |
